Images in slider take a little long to load. I have tried rescaling the image from the media library but I think the slider keeps loading the original size image because I cant seem to tell a difference.

Png images will add a touch of time to your upload, but your overall "issue" if one wants to call it that is not the slider images. You can even see such by inspecting your network and Dom in the developer consoles. It appears the images are taking time to load but it is not in fact the case.

What is happening is that all aspects of your page rendering is not fully resolving until all the google api calls are complete, and because you have 3 gmaps in the page, not only is that taking longer, but in some case specific requests of the api are stalling out, and are going unfulfilled. Gmaps works so that if it goes beyond a certain period of time, then everything finishes loading and leaves the unfulfilled requests in a pending state. But as gmaps is a java based function, and so is the slideshow, the latter does not appear to "set" until all the calls are settled, and so it appears as the culprit, when it is not.

Your welcome. The google api is a little touchy sometimes, which is of course out of control of mere mortals such as you and I (and Striking). Given all the requests I would assume they get every second, sometimes they drop a portion of a request, and when that happens, there is nothing we can do about it.

I have read that the api can consider multiple requests from one url simultaneously spamming, but I consider this unlikely, and I have not yet had time to get to my old buddies at google and find out the real take on this.